Hi, we had our female lab at the vets 8days ago to remove a tumor it was succsesfull ,but now her wound bad?

shes 13 years old, and licking her wound the skin around and inside of her stitchies is now dead skin, this will soon come off, the vet says to let her new dose of anti biotics do there job ,but were getting worried about her health, but she is eating and drinking no problem....thanks CW ..fife scot.